Device for polishing the edge of a glass sheet

ABSTRACT

The invention relates to a device for polishing the edge of a glass sheet. The invention is of the type that comprises: a drive shaft for rotating around the axis of rotation thereof by means of a motor, and a grinding wheel which is connected to the drive shaft in order to polish the edge of a glass sheet. The grinding wheel comprising a groove formed in the outer periphery thereof, which contains a grinding material for polishing the edge of the glass sheet. The grinding wheel is also provided with a plurality of internal passages which extend radially from the centre of the wheel to the outer periphery thereof, in order to enable the passage of a cooling fluid for the cooling of the periphery of the wheel. In addition, a collecting chamber is formed at the centre of the grinding wheel in order to receive and supply the cooling fluid through the passages in the wheel. Cooling fluid supply means are connected to the collecting chamber in order to supply said fluid to the chamber for the cooling of the periphery of the wheel.

FIELD OF THE INVENTION

The present invention is referred to a device for polishing the edge of a glass sheet and more specifically, to a device for polishing the edge of a glass sheet, that includes a grinding wheel with integral cooling passages for the cooling of said wheel.

BACKGROUND OF THE INVENTION

It is well known that sheets of glass, for example, glass for the automotive industry, mirrors, etc. have been cut in keeping with the desired shape, which therefore has to have its edges polished, both for eliminating any possible burrs as well for removing small peripheral fractures that might cause the glass to shatter during the next process that it will be subjected to such as tempering, bending, etc.

Regularly, the edges of the sheets of glass are subjected to a process known as “machining the edge with polishing”, which consists of passing a fine grain polisher or a diamond wheel through the length of the edge of the sheet or glass plate several times. The edge of the sheet has to be maintained humid in order to cool the grinding stone, as well as to prevent the raising of glass dust during the grinding or polishing of the sheet.

In order to maintain the grinding or polishing stone wet, it is necessary that there be a continuous flow of water to cool the grinding or polishing wheel. However, the main problem that is presented with this type of grinders, is that, the outer surface of the grinding wheel has a certain diamond thickness (through which the glass edge is polished), the grinding wheel has to be frequently changed, making continuous stops to the production line, which affects the productivity.

Another problem that presents itself in the grinding or polishing used for sheets of glass is that on some occasions the water does not fall directly onto the grindstone, thus provoking the edge of the sheet of glass to get burnt.

In order to resolve the above, after the sheets of glass have been polished, an operator has to clean them in order to remove any residual that may be left after the polishing operation. However, in some cases, the sheet of glass had already been damaged (by spots or burnt places), and because of this it has to be discarded because it does not comply with the quality standards that are required by the automotive industry.

At present there are already polishing machines for polishing the edge of a sheet of glass, for example, U.S. Pat. No. 4,426,811, of Rudolf Eckardt et al, which refers to a method of grinding glass sheets whose edges are polygons that are not symmetrical about a point. The method is carried out by using an apparatus having a supply station for supporting a stack of sheets in a vertical registration, a grinding station adjacent to the supply station having a grinding table rotatable about an upright grinding axis and adapted to support the sheets of glass during grinding, a template secured to the grinding table, and a pair of grinders in the grinding station radially engageable with the edges of the sheet on its grinding table and radially displaceable by the template. The method of the invention comprises the steps of transporting the sheets, one at a time from the stack in the supply station to the grinding station, simultaneously engaging the grinders with the sheet in the grinding station, while rotating this grinding table with its template and the sheet on the table through a 180 degree to grind the edges of the sheet on the table, so that each such grinding operation displaces the template through 180 degree about the axis. Finally, every other sheet is rotated while being transported from the supply station to the grinding station through 180 degree about an intermediate vertical axis.

The U.S. Pat. No. 4,769,954 of Peter J. Hatas et al, refers to an apparatus for supporting and positioning a planar glass workpiece within a glass grinding apparatus. Three radially extended carriage assemblies are provided between a lower pan and an upper supporting platform. Each one of the carriage assembly extends radially outwardly from a central drive shaft connected to the supporting platform to the periphery of the lower pan. The radial inner ends of the carriage assemblies are rotatably supported about the drive shaft, while the radial outer ends are carried on respective motor assemblies connected to a gear formed on a lower pan. Energization of the motor assemblies causes the associated carriage assemblies to pivot relative to the lower pan. Each one of the carriage assemblies also carries a locator cylinder assembly thereon. The locator cylinder assemblies are movable radially, inwardly and outwardly throughout the length of the corresponding carriage assemblies by means of the associated motor assemblies. Each of the locator cylinder assemblies includes a locator button assembly. Each one of locator buttom assemblies is selectively movable between an extended position and a retracted position. A computer controls the operation of all of the motor assemblies so as to angularly position each of the carriage assemblies and to radially position each of the locator cylinder assemblies, all in accordance with predetermined stored data relating to the particular shape of the glass workpiece.

Notwithstanding that already exist apparatuses for polishing or grinding glass edges of the glass sheets, one of the problems is to solve the cooling and durability of the grinding wheel, this is, to increase the useful life in order to reduce the frequent changes and for increasing the productivity.

There already exist some patents that have developed some concepts on the cooling of grinding wheels for the polishing or grinding, as for example, the U.S. Pat. No. 3,777,443 issued to a Milton C. Shaw on Dec. 11, 1973, describes a segmented grinding wheel assembly, particularly suited for high speed operation. The wheel comprising wheel members having an outer peripheral recess in which grinding segments are positioned to define the grinding or working portion of the assembly. The recess and segments are related so that the segments are held in the recess by compressive reaction forces produced during wheel rotation. Additionally, the specification discloses and arrangement particularly adapted for supplying cooling or lubricating fluid to the wheel periphery. The arrangement comprises an inwardly open, circumferentially extending fluid receiving trough carried by the wheel. The through is connected to the recess by generally radially extending passages such that during wheel rotation fluid moves outwardly to the recess and between the segments under the influence of centrifugal force.

Another invention related with grinding wheels is showed in the U.S. Pat. No. 5,846,125 issued to Henri Robichon on Dec. 8, 1998, which is referred to a grinding wheel having a cooling fluid supply system. The body of the wheel defining a central axis. An abrasive deposit stuck to the peripheral surface of the body. A cooling fluid supply conduit inside the body that comes out into the abrasive deposit by means of several distribution channels that open into a lateral annular chamber and into the abrasive deposit to lubricate the cutting area and cool the wheel, wherein the cooling fluid supply conduit includes two lateral annular chambers, at least two central channels that open into a central chamber and into at least one of said lateral annular chambers, and two opposing sealing covers which define the lateral annular chambers.

Finally, the U.S. Pat. No. 5,993,297 issued to Gregory Aaron Hyatt on Nov. 30, 1999 is referred to a grinding tool for use with an automatic tool changing system in conjunction with a machine spindle and a source of cutting fluid. A preferred embodiment of the grinding tool includes a tool holder adapted for attaching the grinding tool to a machine spindle, and an attachment structure for placing the grinding tool in fluid communication with a source of pressurized fluid. The grinding tool further can comprise a fluid distribution passageway having a central supply tube formed within the tool holder, an annular space and guide channels formed within the body of the grinding wheel, and a plurality of non-perpendicular fluid delivery openings formed in the grinding surface so that coolant fluids at pressures of 200 psi and greater can be received within the fluid distribution passageway and delivered in a controlled manner toward the grinding surface via the delivery openings for either cleaning the grinding surface, for cooling and otherwise lubricating the workpiece and the grinding tool, or both.

However, notwithstanding that there are diverse equipments and inventions related with grinding wheels for different uses, the grinding wheels that includes cooling are very complex, in view that includes the formation of chambers, caps, etc, which make that the manufacture of the grinding wheel be very expensive.

Furthermore, due to the complexity of the previous art grinding wheel, there is not possible to increase the grinding area to increase the useful life, in view that the fact that the grinding wheels contain cooling chambers impeded to increase the depth of the grinding area and with this to increase the useful life of the grinding wheel.

Finally, the majority of the grinding wheels contain a protecting cover to protect the user of any rupture or to avoid an accident.

In the glass industry, normally the grinding wheel is enclosed in a hollow housing, which comprises a lateral slot through which is introduced the edge of a glass sheet for contacting the grinding wheel. Due to the diversity of forms of the glass sheet, when the polishing or grinding of the edge of the glass sheet is started, the housing is adjusted to the movement of the glass sheet, that is, the housing has to be radially moved in accordance with the form of the glass sheet, to avoid the collision of the housing with the edge of the glass sheet.

In accordance with the above, one of the objectives of the present invention is to provide a device for polishing the edge of a glass sheet, which includes a grinding wheel with cooling passages and a movable housing to provide a cooling fluid to said grinding wheel.

The device for finishing the edge of a glass sheet is of the type that comprises a support structure, which includes a support base, a stationary vertical structure that is supported over the support base, and a supporting upper arm located in a horizontal position on the stationary vertical structure; a motor provided in a fixed manner at an end of the free supporting upper arm, said motor including a drive shaft supported in a vertical position for rotating over its own axis by the movement of the motor; a grinding wheel or a diamond wheel connected to the drive shaft to finish the edge of a glass sheet, said grinding wheel having a plurality of passages which are radially extended for supplying a cooling fluid for the cooling of the grinding wheel; a tubular element axially coupled around of said drive shaft; a housing for housing the grinding wheel or diamond wheel, said housing having a lateral slot through which the edge of the glass sheet is introduced to make contact with the grinding wheel, said housing being coupled to said tubular element to be radially moved in accordance with the periphery of the glass sheet; and feeding means of a cooling fluid to conduct the cooling fluid by the central part of the grinding wheel and making to flow through the cooling passages for the cooling of the grinding wheel.

OBJECTIVES OF THE INVENTION

A first objective of the present invention is to provide a device for polishing the edge of a glass sheet which includes a grinding wheel having cooling passages, for the continuous and uniform cooling of the wheel.

Other additional objective of the present invention is to provide a device for polishing the edge of a glass sheet, that due to its configuration, permits to increase the depth of the grinding section (diamond), increasing the useful life of the grinding wheel and so minimize the production stops by change of said grinding wheel.

An additional objective of the present invention is to provide a device for polishing the edge of a glass sheet, which avoid the burning of the edge of the glass sheet, due mainly to a direct and continuous flow of the cooling fluid on the glass sheet.

These and other objectives and additional advantages of the present invention will be evident to those persons who are experts in the field of the following detailed description of the invention, which will be made with reference to a specific embodiment of it in an illustrative sense but not one that would limit the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a lateral view that shows, in a schematic manner, a device for finishing a sheet of glass in accordance with the present invention.

FIG. 2 is a sectional lateral of the device for polishing the edge of a glass sheet, in accordance with the present invention;

FIG. 2A shows a first detailed view of the upper part of the device illustrated in FIG. 2;

FIG. 2B shows a second detailed view of an inferior section of the device illustrated in FIG. 2;

FIG. 3 is a view in a conventional perspective of a grinding wheel in accordance with the present invention;

FIG. 4 is a view plant view showing the upper part of a grinding wheel with cooling passages, in accordance with the present invention;

FIG. 5 is a view in lateral elevation of the grinding wheel illustrated in the FIG. 4; and,

FIG. 6 is a sectional partial view of the montage of a wheel supporting and grinding wheel in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Now follows a reference to a specific embodiment of the present invention that is illustrated in the figures which are attached and where the same numbers refer to the same parts and wherein FIG. 1 is a lateral view that shows, in a schematic manner an apparatus 10 for finishing a sheet of glass 28. The apparatus 10 including a support structure 12, which includes a support base 14, a stationary vertical structure 16, coupled on the support base 14, and an upper supporting arm 18, located in a horizontal position on the vertical stationary structure 16. A motor 20 is connected at one end of the free supporting arm 18. The motor 20 including a drive shaft 22, located in a vertical position to rotate over its own axis by the movement of the motor 20.

The drive shaft 22 is connected with a grinding wheel 24, on its lower part, for finishing or grinding the glass edge 28. A tubular structure 30 is connected to the motor structure 20, which is vertically positioned for covering the drive shaft 22. A hollow housing 32 (FIGS. 1 and 2) for housing the grinding disc 24, which comprises a lateral slot 34, through which is introduced the edge 26 of the glass sheet 28 for making contact with said grinding wheel 24.

The device for finishing or grinding the edge of a glass sheet 28, is used in combination with a rotatable work table 36. The edge 26 of the glass sheet 28, overextends the periphery of the rotatable work table 36, and is placed towards and coincidence with the grinding wheel 24, of the device 10 illustrated in the figure. The rotatable work table 36 rotates on its own rotatable axis through a shaft 38, operated by a motor (not shown). In this way, when the grinding wheel 24 makes contact with the edge 26 of the glass sheet 28, a grinding or finishing operation for finish the edge 26 of the glass sheet is carried out.

Making now particular reference to the FIGS. 2, 2A y 2B, is showed a lateral sectional view of the improvements in the device for finishing the edge of a glass sheet in accordance with the present invention. As it is schematically showed in the FIG. 2, the grinding wheel 24 is formed in a single casting piece, which is coupled in the lower part of the drive shaft 22, said grinding wheel 24 being driven with uniform rotation movement through a motor 20. Said grinding wheel 24 including a plurality of passages 40 that are internally formed in the body of said grinding wheel 24 which are equidistantly distributed from a central section PC to an outer periphery PE of said grinding wheel 24. Notwithstanding that the distribution of the passages 40 is showed in a lineal form, said cooling passages 40 can be distributed with an angular position (not showed) from the central opening PC to the outer periphery PE of said grinding wheel 24. Said passages 40 permitting the pass of the cooling fluid for cooling the outer periphery PE of the grinding wheel 24. A tubular element 42 coupled coaxially around of said drive shaft 22, the housing 32 having a lateral slot 34 through is introduced the edge of the glass sheet 26 to make contact with the grinding wheel 24, said housing 32 being coupled to said tubular element 42 to be radially moved in accordance with the periphery of the glass sheet 28. The housing 32 comprises a fixed upper section 32A and a movable lower section 32B. The fixed upper section including a top cover 44 and a first circular chamber 46 (FIG. 2A) located below of the top cover 44 to be moved with an oscillatory movement around the tubular element 42. The first chamber 46 is utilized to receive a cooling fluid, i.e. water, by means of a first pipe 48 through of the top cover 44. A second pipe 50 is connected by a first end 52 in the lower part of the first chamber 46 and a second end 54 that is located in coincidence with a second chamber 56, which is fonned when the grinding wheel 56 is coupled with the drive shaft 22, as will be showed in detail in the FIG. 2B. Said second pipe 50 provides the cooling fluid to said second chamber 56, in order to be supplied trough the cooling passages 40 for the cooling of the outer periphery of the grinding wheel 24. Making now reference to the movable lower section 32B of the housing 32, this includes a bearing R to permit an oscillatory movement of said movable lower section 32B with respect to the fixed upper section 32A. A gear E is coupled in the periphery of the movable lower section 32B and pinion P is coupled to said gear E for transmitting an oscillatory movement of the movable lower section 32B. The gear E and pinion P system is connected to a drive system (not showed) that is programmed to determine the degree of turn of the movable lower section 32B in accordance with the profile of the glass sheet 28.

Making particular reference to the FIG. 2A, is showed in a detailed form the coupling of the housing 32 with the tubular element 42. As is illustrated in the figure above cited, a support 58 in the forma of a “T” is parallel coupled to the wall of the tubular element 42. A section of the support 58 is perpendicularly placed with relation to the tubular element 42, so in this way, the cover 44 is placed on the perpendicular section of the support 58 to rest on said support 58. The first chamber 46 includes a first circular housing 60 used for the storage of water and a second housing 62 for the coupling of a bearing 64, between the support section 58 and the first chamber 46, to permits the free rotation of said chamber 46 with relation to the support section 58. In this way, the first chamber 46 is moved with an oscillatory movement in accordance to the movement of said movable lower section 32B through of the second pipe 50.

Making now reference to the FIGS. 2B, 3, 4, 5 and 6, the grinding wheel 24, made of a single piece is showed in a detail form. The grinding wheel 24 includes a groove 66 formed in the outer periphery. Said groove 66 having a grinding material 68, which is agglutinated and formed in the groove 66 for forming the grinding surface 68, said grinding material being contained between the walls 70, 72, of the groove 66. However, notwithstanding that a size of groove 66 is showed, it is possible to increase the depth and width of the groove 66 in order to increase the grinding surface 68 and so, to increase the useful life of said grinding wheel 24, i.e. the groove 66 can be manufactured with a depth from 0.10 inches to 1 inches in order to increase the surface o grinding material. A plurality of cooling passages 40, said passages 40 being internally formed in the grinding wheel 24, which are radially extended from the center to the outer periphery of said grinding wheel 24, to enable the pass of the cooling fluid for the cooling of the periphery of the wheel 24, said passages 40 also crossing the grinding surface 68.

The grinding wheel 24 includes three drill holes 74, through which three screws 76 (FIG. 6) are placed in order to hold the grinding wheel 24 at the lower part of the drive shaft 22. A fasting plate 78 with a central hole 80 is placed below the grinding wheel 24 to retain said grinding wheel 24. The fastening plate 78 forming together with grinding wheel 24, the second chamber 56 to receive the cooling flow in order to be expelled through the cooling passages 40, for the cooling of the periphery of the grinding wheel 24. As is shown in detail in FIG. 2B, the fastening plate 78 includes a rotatable sleeve 82 that is coupled by one end in the central hole 80 and by the other end to the pipe 50.

Finally, as can be observed in the FIG. 6, the drive shaft 22 includes a separable section 84, which is coupled and discoupled in the drive shaft 22 to facilitate the change of the grinding wheel 24.

As can be seen from the embodiment above described, a device for finishing or grinding the edge of a sheet of glass has been described, which permits to increase the useful life of the grinding wheels. However, it must be understood that the invention should not be limited to the embodiment above described, and it will be apparent to the experts in the field that other diverse embodiments could be implemented, along with alternative embodiments which will be clearly contained within the spirit of the present invention which are claimed in the following claims. 

1-8. (canceled)
 9. A device for grinding the edge of a glass sheet which comprises: a drive shaft to rotate about its own axis by means of a motor; a grinding wheel of a single piece, having an outer periphery and a central opening, said grinding wheel being connected to the drive shaft for rotating with the shaft, in order to polish the edge of a glass sheet, characterized in that the grinding wheel comprises a groove, said groove being formed along the outer periphery of said wheel, said groove having a depth from 0.10 to 1 inches, said groove being filled with a grinding material, which is binded in said groove for forming a grinding surface to polish the edge of a glass sheet; and, a plurality of cooling passages, said passages being internally formed in the grinding wheel from said central opening to the outer periphery and grinding material, said passages being equidistantly distributed from the central opening to the outer periphery in order to enable the pass of a cooling fluid for the cooling of the outer periphery of the grinding wheel, said central opening receiving the cooling fluid that will be supplied through of said plurality of passages for the cooling of the grinding wheel.
 10. The device for grinding the edge of a glass sheet as claimed in claim 9, wherein the grinding wheel further includes, means to provide a cooling fluid, said means to provide the cooling fluid being connected to the central opening of the grinding wheel to provide the cooling fluid to each one of the cooling passages of the grinding wheel, said means to provide the cooling fluid being characterized by, a first circular chamber which is attached to be moved radially about a fixed tubular element, said fixed tubular element being coaxially located with relation to said drive shaft, said first circular chamber being prepared to receive the cooling fluid; first cooling fluid supply means connected with said first chamber to supply the cooling fluid to said first chamber; second cooling fluid supply means connected between said first chamber and said central opening of the grinding wheel, in order to supply the cooling fluid from said central opening to the outer periphery of the grinding wheel; and a plate coupled to said second cooling fluid means, said plate having a central hole to permit the entrance of the cooling fluid, said plate being coupled below the central opening of the grinding wheel.
 11. The device for grinding the edge of a glass sheet as claimed in claim 9, wherein the cooling passages in the grinding wheel are in a position slightly inclined from the central opening to the outer periphery.
 12. The device for grinding the edge of a glass sheet as claimed in claim 10, further includes a hollow housing for housing the grinding wheel, said housing being coupled around of the tubular element, said housing having a longitudinal groove through which the edge of the glass sheet is introduced for contacting with the outer periphery of the grinding wheel, said housing having a radial movement that is independent of the drive shaft movement. 